foojay — a place for friends of OpenJDK

A Real-World Example of a Stream Collector

You can solve most use cases with one of the out-of-the-box collectors provided in the Collectors class.

However, some require to implement a custom Collector, e.g., when you need to collect more than a single collection or a single scalar.

While it may seem complicated if you never developed one before, it’s not. You only need a bit of practice.

I hope this article might help you with it!

Preventing YAML Parsing Vulnerabilities in Java

YAML is a human-readable language to serialize data that’s commonly used for config files. The word YAML is an acronym for “YAML ain’t a markup language” and was first released in 2001. You can compare YAML to JSON or XML as all of them are text-based structured formats.

YAML files are often used to configure applications, application servers, or clusters. It is a very common format in Spring Boot applications and, of course, to configure Kubernetes. However, similarly to JSON and XML, you can use YAML to serialize and deserialize data.

Payara Services Wins Prestigious Queen’s Award!

Micro-multinational open source software company, Payara Services, has been commended for its achievements within global trading and exporting with the Queen’s Award for Enterprise for International Trade.

Now in its 55th year, the Queen’s Award for Enterprise: International Trade is the UK’s most prestigious business award, honouring organisations that have excelled in overseas exports whilst maintaining the highest standards in social, economic, and environmental activity.

Elastic JVM: Configuring G1 GC for Automatic Vertical Memory Scaling

Nowadays, JVM-based applications can benefit from elasticity and density of container technology. However, there are still some issues that prevent unleashing the full potential of Java and containers “marriage.”

Releasing unused but committed Heap memory by the major JVM implementations based on OpenJDK, in most cases, is not performed automatically, or requires specific knowledge to be configured.

Why Java Developers Continue to Rely on Jakarta EE

Over the past year, the Eclipse Foundation spoke to leading Java developers around the world to discuss why they rely on Jakarta EE and the unique benefits of using Jakarta EE technologies.

Their input is captured in our white paper, which describes the important advantages Jakarta EE offers today and for the future.

Creating a Snake Game with JavaFX FXGL in Three Pair-Programming Sessions

In this article, Almas and Frank show you how to start with an idea for a game and bring it to life in a prototype application. We will then modify the application to run on a Raspberry Pi and on a mobile device.

To give some background, some time ago my 10y old son challenged me to create a Snake-like game with emojis. He selected the emoji images and I “only” needed to do the programming bit, the easy part… Luckily Almas asked me if I had a topic for some pair-programming for his YouTube channel, and his question turned into a three-part series. My son is delighted because his idea is now a real game!

New Book: “Java Challengers”

To get the best jobs and create massive value, you need to know Java very well. The newly released “Java Challengers” book is a way for you to challenge yourself with fun code challenges so that you will become a better Java developer.

This book contains more than 70 well-elaborated Java Challenges that will help you break your limits on your Java skills. Want to challenge yourself and become better? The Java Challenges is the book for you!

For each Java Challenge you get a full explanation to fully prepare you to beat the Java Challenge!

To tease you with the Java Challenges book, try out the following challenges and see if you can solve them…

A Close Look at Kotlin’s Delegation

Kotlin offers many exciting features.

In general, developers tend to cite null safety as their favorite. For me, it’s function extensions. But delegation comes a close second.

The delegate pattern is ubiquitous in the Object-Oriented Programming world. Some languages, such as Kotlin, provides a native implementation.

But delegation doesn’t stop at the class level. Kotlin does provide delegation at the property level. It provides some out-of-the-box delegates, but you can easily create your own.

New to Java? Some Resources

I was asked if I had a list of resources for developers who are new to Java. I didn’t at the time, but I’ve spent some time researching and here is that list.

I’ve listed content that is both free and paid. It’s not that one type is superior; it’s just to give you plenty of choices. These are the resources that I’ve used and do still use to re-learn Java. So, if you’re new to Java or looking to pick it up again after a break, this article is for you.

The other super important point is that everyone learns differently; some like reading, some like doing, some like watching, most of us like a bit of a mix of everything. I tend to switch between them depending on what I want to learn about and how I feel. You’re probably similar, so pick an approach that works for you.

Fix Java Security Issues While Coding in IntelliJ IDEA

Nowadays, developers are responsible for more than just creating the application. Besides working on features, developers have to focus on their applications’ maintainability, scalability, reliability, and security. Many developers are unsure of where to start with security. In addition, most companies still work with a dedicated security team instead of having security expertise inside the team.

A lot of developers practically live in their integrated development environment (IDE). A good IDE is like a swiss army knife: it is your go-to tool to do almost everything. Having everything I need to build, run, test, debug, and secure my application, makes a good IDE invaluable for many developers.